It is known to treat female urinary incontinence with electrical stimulation applied to the walls of the vagina via electrodes carried by a probe inserted into the vagina. See, for example, Eriksen and Eik-Ness, Long-Term Electrostimulation of the Pelvic Floor: Primary Therapy in Female Stress Incontinence, 44 Urology International 90-95 (1989); Fall, Does Electrostimulation Cure Urinary Incontinence?, 131 The Journal of Urology 664-667 (1984). By activating pudendal nerve branches, such stimulation causes contraction of the muscles of the pelvic floor. Repeated sessions of such stimulation can strengthen and retrain those muscles and thereby alleviate stress incontinence in which urine passes with the onset of abdominal pressure which may result from stressed or quick activities, including sneezing and jumping. Repeated sessions of such electrical stimulation can also alleviate urge incontinence, which results from involuntary bladder contractions; the electrical stimulation apparently inhibits reflex actions of the various pelvic nerves which are responsible for bladder control.
An electrode-carrying insert has also been used in electromyographical biofeedback treatments. In those usages, the electrodes on the insert transmit electrical signals in the other direction--i.e., the electrodes detect from the vaginal or rectal wall the minute electrical impulses resulting from muscle activity and transmit those impulses to electrical components which display them to the patient. The patient utilizes the display in a biofeedback process to develop conscious and willful control over his or her muscles. U.S. Pat. No. 4,396,019, Perry, Jr., Aug. 2, 1983.
One type of intravaginal electrode-carrying insert is relatively rigid. It will accommodate electrodes in the form of bands around the insert, which optimizes the effectiveness of the insert in delivering the signals to the vagina wall. See e.g., U.S. Pat. No. 4,881,526. With this type of insert, it is typically the practice to provide a wide variety of sizes in order to be able to fit each individual patient. Even if a proper fit is initially made, it may cease to fit well because of changes in the size of the woman's vagina which can result from changes in body position and hormone levels. In these cases, and even in well-fit cases, maintaining the insert in proper position for effective transmission of electrical stimulation to the targeted portions of the vaginal wall has been a problem. A further problem of the rigid insert is that insertion can be difficult since the insert is rigid and must be large enough to effectively contact the body cavity walls.
The ideal electrode-carrying body cavity insert would (a) fit body cavities of different sizes, (b) be easily inserted, (c) remain at the desired location in the body cavity, (d) provide good electrical contact with the body cavity walls and (e) be easily removed. The last two decades have seen numerous efforts to meet this ideal:
______________________________________ Date* Country Doc # Inventor Insert Feature ______________________________________ 1974 U.S. 3,866,613 Kenny Adjustable ring 1976 U.S. 4,106,511 Erlandsson Inflate inside cavity 1978 U.S. 4,296,760 Carlsson Inflate inside cavity 1983 FR 2,547,203 Pigne Foam provides structure 1989 U.S. 5,010,895 Maurer Rolled-up sheet 1992 WO 93/24176 Tippey Inflate inside cavity Tippey Foam provides structure ______________________________________ *The date is the priority date.
This effort was not entirely successful. Mechanically adjustable inserts, such as the adjustable ring and the rolled-up sheet, can be inconvenient and uncomfortable to use and may not make full and consistent contact with the walls of the body cavity. The inflate-inside inserts can be relatively convenient to insert and remove, but require the maintenance of air pressure during the entire period of use (which requires greater manufacturing expense to prevent leakage), and when rigid enough to make effective electrical contact, they may be too rigid to adapt to the exact shape and size of the particular body cavity, resulting in partial and inconsistent contact with the walls of the body cavity. The foam-filled inserts do not require the maintenance of air pressure during use and can adapt to the cavity, but they are more difficult to insert and remove since it is in its expanded state during insertion and removal.
Parallel with this effort, in 1984 (U.S. filing date) there was developed a non-electric vaginal insert to enhance the effectiveness of Kegel-type vaginal exercises. U.S. Pat. No. 4,653,514 (Shapiro, Mar. 31, 1987). The electrode was filled with a foam to provide resistive force to the vaginal walls, against which a women could exert her pelvic muscles and thereby strengthen them. To provide beneficial exercise, the foam had to be relatively stiff. To facilitate insertion and removal of an insert filled with such foam, the insert was provided with a pump to evacuate the air from, and thereby collapse, the insert. When the insert was in place, the vacuum was released and the foam expanded to the vaginal walls and thereby held the insert in place without the need to maintain air pressure during use.
The foregoing chronology shows that, five years after the publication of the Shapiro patent, persons skilled in the electrode-insert art (such as Tippey, et. al) continued along the well trod path, developing an improved inflate-inside electrode-insert and an improved foam-filled electrode-insert. There remained a need for an electrode-insert which overcomes the disadvantages of these devices.